Resistance device.



mmszmss. PATENTED JULY 31, 1906.

H. W. LEONARD. RESISTANCE DEVICE.

APPLIOATION FILED MAYl3 1905.

2 SHEETS.SHEET 1.

ami/mum 7/ f 344De4foz 47 $51 Gwen/wig BIO-827,455. PATENTED JULY 31, 1906. H. W. LEONARD.

RESISTANCE DEVICE.

APPLICATION FILED MAY 13, 1905.

2 SHEETS-SHEET 2.

Witt moms avwemfoz I 1 W W HARRY VVABD LEONARD, OFBRONXVILIAE, NEW YORK.

RESISTANCE DEVlGE Specification of Letters Patent.

Fatented July 31, 1908.

Application flled May 13, 1905.- Serial No. 2ao.197.-

To all whmn it may concern: I f

Be it known that I, HARRY WARD LEON Am), a citizen of the United States, residing at Bronxville, in the county of Westchester and State of New York, have invented certain new and useful Im rovements in Resistance Devices, of which t e following isa full, clear, and exact specification.

My invention relates principally to devices in which electric energy is intentionally converted into heat, such as resistance units,-

rheostats, electric heaters, &c.

My invention is particularly applicable to resistive conductors, which are formed of a fine wire and made of amaterial which is very susce tible to oxidation or equivalent chemical e reciation. When using a very fine wire, t e resistance may be compara tively high; but to get the very high resistances desired in practice it is very advantageous to make the fine Wire of a material having the highest possible specific'resistance. The material I prefer to use which has a very high specific resistance is an alloy generally containing iron, manganese, or similar metal and which very rapidly depreciates if exposed to moist air, salt air, gases containingsulfur or. other agencies, which. might combine with the very susceptible material of the alloy. This is particularlytrue, in that alloys of this character are not very homogeneous in their nature, and consequently there are occasional places in such Wires where the lack of homogeneity of the alloy results in this tendency to rapid chemical depreciation.

One Way of protecting and supportingresistance-wires is by coating the wire with a vitreous enamel, which adhesively attaches the wire to a supporting-tube. When fine Wires are employed, particularly when made of alloys above referred to, it is important to keep the heat of manufacture down to a minimum and to use the minimum numberof metal and partially non-metallic.

v reach the sensitive fine wire, and this is probably the reasomwhy protection from chemical depreciation is not perfectly attained with such construction. found it necessary after manufacturing the high-resistance tube as carefully as possible to rovide additional protective means which wil remedy the difficulty abovetreferred to. This I accomplish by surrounding the resistance-tube with a material which shall be practically non-hydroscopic. The material which I prefer to use for this surrounding material is a-pure grade of white silicious sand,

and this is preferably again surrounded by a casing which is hermetlcally sealed as perfectly as can be accomplished by ordinary processes, such as by a joint of putty or some equivalent material. With this construction I am able to employ wires which are as fine as can be drawn, even when made of alloys'of very high resistivity above referred to. I thus obtain a very compact, inexpensive, and efficient form of resistance, which is desirable,

in certain types of apparatus. I have found that it is impossible to attain this result commercially by using a very fine wire of such material when merely embedded in sand, and also that it is impossible to attain the result when such a wire is protected by enamel or other character of coating. It is only by combining these fine wires embedded in a suitable coating with the surrounding sand or e uivalent surroundin material that the resiilt can be commercia 1y attained. I prefer to use iron or steel for the inclosing case; but in some instances the case may be partially I sometimes use aiplurality of resistance units in one case.

One important application of my invention is in connection with the starting and protective devices for motors, as will be further explained. Gther applications are in the construction of devices 111 which the heat developed. in the resistive conductor must be I00 efficientlyconducted to the surface which is to be maintained at a hi h temperature, such as in certain forms of rneostats, solderin -irons, fiat-irons, and cooking utensils.

11 many cases it may be desirable to oper- 1o 5 ate the resistive conductor under such conditions that the conductor is burned out in the r course of time, and is expected to, and I therefore provide means for simply and quickly replacing the resistance unit. I For no I have, therefore,

p out.

and relatively short life and renew the resistance unit when it is burned out in a simple and inexpensive way rather than to attempt to make a soldering-iron which will not burn My invention will be understood and will be explained with reference to the accompanying drawings, in which- Figure 1 is a face View of a motor-starting device provided with protective'uneans and showing the electrical connections. Fig. 2 is a rear view thereof with the casing removed. Fig. is a sectional view of the starting device. Fig. 4 is a longitudinal sectional view of a single resistance unit having its own individual casing. Fig. 5 is a part-sectional and part-side view of a soldering-iron em-' bodying my invention. Fig. 6 is a part-face and part-sectional view of a flat-iron embodying my invention. Fig. '7 is an end view of the face of the flat-iron. Fig. 8 is a sectional view, and Fig. 9 an elevation, of a modified form of my invention.

Referring to Fig. 1, the panel of the motorstarter, which is preferably slate, is indicated at '1 and is provided with resistance-contacts 2, over which the resistance-controlling arm 3 passes. The arm 3 is connected with the overload-switch 4 by a spring 5, tending to force them toward each other. The resistance-arm is retained in its final position by the novoltageretaining magnet 6, which is connected in an independent circuit across the line in series with a high resistance 7. In running position, as shown, the overload-arm 4 is retained by a latch 8, which is adapted to be tripped to release the arm by the overload-coil 9, the circuit then being broken between the arm 4 and the contact 10. The current passes from one supply-line through the overload-coil 9, contact 10, arms 4 and 5, through the armature resistance ,1 1 when starting, and through the armature A to the other side of the line. The field-winding F is connected from the initial resistance contact in an independent circuit across the line, and the no-voltage magnet 6 is also connected in an independent circuit across the line through the high resistance 7, as above stated. This form of connection is veryadvantageous as compared with connecting the no-voltage magnet 6 in series with the field-winding F, as has been common practice. I A considerable difficulty is met with in providing an efficient and economic high resistance 7 for connecting in series with the no-voltage magnet, particularly on high voltages. My present invention is particularly applicable for obtaining the result desired, .and by practicing the same I have no difficulty in obtaining satisfactory results with voltages of six hundred and upward.

The resistances 11 are shown in Figs. 2

and 8 as bare wire in spiral form suspending between studs 12. These may be arran ed in any suitable manner, and in order to preserve their life and to increase theircapacity are embedded in sand 13, the whole being inclosed by an iron casi'n 14. The resistance 7 isalso placed within t e casing and embedded in sand and is made up of a porcelain tube with a very fine wire wound thereon, the wire being made of an alloy having a very high specific resistance above referred to and embedded in a coating of vitreous enamel. The resistance-tube is indicated by the reference character 15 and is suitably fixed in position. An opening is provided at the top of the casing 14 for introducing the sand into the casing, which opening may afterward be closed with a screw-plug. The sand should be thoroughly dried before introducing into the casing.

By the above construction I not only secure the advantage of embedding the starting resistance in sand, but by combiningin the same casing the enameled high-resistance unit I secure a commercial form of resistance adapted to be connected in the circuit of the no-voltage magnet across the line.

In Fig. 4 I have shown the enameled resistance unit 15 inclosed in an individual casing in the form of an iron tube 16. The -re sistance unit is supported in place upon a rod 17, and over the ends of the iron case 16 are placed caps 18, of asbestos, and sheet of mica 19. A porcelain bushing 20 fits within the mica and asbestos cap and serves as a guide for the rod 17. The terminals of the resist ance unit are passed out between the ends of the iron case and the asbestos caps 18. The nuts 21 are threaded out: the endsof the rod 17 to hold the arts firmly together, and a support 22 is c amped between the nuts 21 and outer nuts 21. The space between the resistance-tube and the inclosing case is filled with sand 13.

The soldering -iron, shown in Fi 5 is formed of the usual outer part 23, w -'ch in this case is hollowed out to receive the hi hresistance unit 15 and which is surroun edwith the sand 13. The resistance unit is supported on a rod 24, which passes into the end of the soldering-iron. The resistancetube is held in position by the nut 25. A cap 26 is adapted to-fit over one end of the soldering-iron and is fixed thereto by anut 27 on the rod 24, which serves to clamp the parts together. The sand may be introduced into the chamber of the soldering-iron through the opening closed by the screw 28.

Onto the part 26 is screwed a bushing 29,

which in turn receives a perforated metal part 30 for dissipating the heat, so that it will not be transmitted to the handle. The leads from the resistance may pass through the soldering-iron through suitable openings'out through the flexible guide 31 at the end of eated.

ihe handle. The leads may be insulated and pron-cred by glass beads thereon, as indi- The flat-iron shown in Figs. 6 and '7 comprises a series of holes bored or drilled into the iron 32 and the enameled resistance .in-its, which are supported one in each openmg by a screw-bolt 33, which engages the inner end of the openings. The insulatingsupports for the resistance are preferably provided with projections 34 at the ends in order to properly space and position the resistance units. The end of the iron is capped by a plate 35, which is removable and which is provided with lava bushings 36 for receiving the leads to the resistances. A screw 28 closes an opening adapted to be used for fillin g in the sand.

The form of resistance device shown in Figs. 8 and 9 is' adapted for use in apparatus, such'as a heater or a rheostat. This form comprises a casing composed of thin metal 37 in two similar parts, which'when joined together form a series of tubular openings. Each opening is adapted to receive a resistance unit of the type described, having the tubular support 38 and a coating of enamel 39 for embedding the resistance-wire. The

. support 38 preferably has projections 34 for positioning the unit in the center of the opening. The remaining space is filled with the sand 13 or other suitable material. The leads from the resistance units maybe passed through suitable notches or openings and protected by glass beads. The device is closed by caps 40 at the ends, a suitable joint being provided so as to seal the device as a whole. The screws 2S'may be provided for permitting the insertion of the sand.

It Will be understood that the resistive conductor, its support, its insulation, its protective material, the removable material, and the case may be varied in form andconstruction, and I therefore do not wish to have the scope of my invention limited, except as the claims indicate.

Having thus described my invention, 1 declare that what I claim as new, and desire to secure by Letters Patent, is

1. The combination of a resistive conductor, a support for the same, a protective and insulating material embedding the conductor, and a casing inclosing, protecting and her metically sealing the parts.

2.- The combination of a resistive conductor, a support for the same, a coating embedding the conductor, an inclosing casing and a protective filling material surrounding the resistance unit within said casing.

33. The combination of a resistive conductor, a support for the same, a coating embedding the conductor, an. inclosing casing and sand surrounding the resistance unit within said casing.

4. The combination of a tubular enameled resistance unit the resistive conductor being of fine wire and an alloy having a very high specific resistance, an inclosing casing, anda protective filling material surrounding said resistance unit within said casing.

5. The combination of a tubular cnameled resistance unit, the resistive conductor be ng offine wire and an alloy' having a very high specific resistance, an inclosing cas ng, and sand surrounding said resistance unit within said casing.

6. The combination of a motor-starting rheostat, a high resistance adapted to be connected in a circuit across the supply-line 1ndependentl of the resistances of said rheostat, a sing e casing for inclosing the start ng resistances and said high resistance, said high resistance comprising a resistance unit embedded in an adhesive protective insulatmg material, and a protective filling material within said casing and surrounding sa d startin resistances and said resistance unit.

- 7. T 1e combination of a motor-starting rheostat, a high resistance adapted to be connected in a circuit across the supply-line independently of the resistances of said rheostat, a single casin for inclosing the start ng resistances and sai high resistance, said hlgh 'resistance'comprising a resistance unit embedded in an adhesive protective insulating material and a filling of sand within said casing and surrounding said starting resistances and said resistance unit.

8. The combination of a motor-starting rheo'stat, a high resistance adapted to be connected in a circuit across the supply-line independently of the resistances of said rheostat, a single casin for inclosing the starting resistances and said high resistance, said high resistance comprising a resistance unit embedded in an adhesive protective insulating.

material, and a solid mobile insulating ma terial Within said casing and surrounding said starting resistances and said resistance unit.

9. A resistance device comprising an enameled resistanceunit, sand surrounding said unit, and an inclosing casing, the said parts being adapted to permit the removal of said unit.

10. A resistance device comprising a resistance, a protective insulating material embedding said resistance, an inclosing casing, and a solid mobile insulating material. surrounding said embedded rcsistance and within said casing.

11. The combination of a resistive conductor, a protective adhesive insulating material embedding the conductor, an inclosing casing, and an insulating protective filling of material interposed between said embedded conductor and the inclosing casing.

12. The combination of a resistive conductor, a protective adhesive insulating matei casing, and an insulating protective solid I bedded between the adjacent turns of said 1 conductor, an inelosing casing, said embedded conductor being adapted for removal. from said casing, and solid protective insulating material interposed between said embedded conductor and said casing.

In testimony whereof I affix my signature in presence of two witnesses.

H. /VARD LEONARD. Witnesses:

L. K. SAGER, GEO. A. HOFFMAN 

